3 Answers
3

Requires extreme finessing of the ship's safety systems in order to stop the ship from (quite rightly) aborting the process.

Since the X-wing is a small fighter craft and since the pilot usually makes it go by simply telling their astro-droid where they want to go, it seems likely that an X-Wing's hyperdrive isn't able to be tricked in the same way that the Falcon's can be.

Human and Wookiee hands flew over the main console, supplementing as
best they could the approach and landing information they had
preprogrammed into the Falcon’s instrumentation. Not unexpectedly,
more than one last-second override was required in order to make the
ship do something that was against its nature and perform maneuvers
for which it had never been designed.

The idea of approaching and landing on a planet at light speed is clearly something that is considered insanely dangerous. It seems like most people don't even believe it's possible, until Han agrees to try.

It's been well established over the course of the movies that Han is an extraordinary pilot -- he constantly does things with the Falcon that are not normal flight maneuvers. (Piloting the asteroid field, for example). So for him to risk just himself and his one ship on the attempt is worth the risk.

Risking the entire fleet trying to pull off the same stunt is a bad idea; for starters, every ship has different maneuvering characteristics; it's not even clear every ship could make that landing safely. And even if the ships were technically capable of it, it's not something you'd want pilots to try for the first time en masse -- if they screw up, the Resistance loses it's entire remaining fleet and the First Order wins.

It's important to note that, while the movie ignores some plot holes like this, TFA actually covers it.

The Falcon just barely makes it, and it had the structure to take the crash landing. An X-Wing would not fare that well. It's also noted that this is not exactly a sane plan, or it would have been the plan.

The team gets into the regulator and Chewie sets off a sizable explosion, which fails to destroy the regulator. Only an X-Wing was able to destroy it. So you need the shield's down.